Made from closed cell neoprene to insulate heat and repel water. The pouch secures placement of the Hot Hands packet over the inside of the wrist to warm the blood flowing to your fingers. The hot hands are specially designed to be place directly into the pouch and will continue to warm for up to 6 hours.The added beneifit is that the slow heat release provides relief to sore wrist and forearms and in some cases provide relief to Arthritic joints in the hand. Make the Great Outdoors or cold Indoors more enjoyable. Sizes are similar to glove sizes but they do expand.